1. Field of the Invention
This invention relates to a projection display that displays color images.
2. Description of Related Art
Conventionally, projectors are used in presentations at business meetings, academic conferences, exhibitions, or other events or for watching movies at home. Such projectors modulate light, which is emitted from a light source provided in an external case of the projector, on the basis of image information to form an optical image, and magnify and project the optical image. In order to display the projected optical image more sharply, it is required of a light source lamp of recent projectors to provide higher brightness.
High pressure mercury lamps, metal halide lamps or the like are used as the light source lamp of the projectors. However, these lamps are disposable and require replacement. In addition, if an arc tube made of quartz or the like is use, it may explode as the lamp approaches the end of its life span, scattering its broken shards within the projector. Further, as the light source lamp generates a higher brightness it also generates greater heat, and therefore a means of expelling the generated heat outside to cool the light source lamp is needed to prevent the explosion of the light source lamp.
In the conventional light source devices having a cooling mechanism for a light source lamp, the light source device as disclosed in Japanese unexamined patent publication No. 2004-258211 is known. FIG. 14 is a schematic view of the conventional light source device. Referring to FIG. 14, the conventional light source device 400 includes a light source 401, a reflector 402, a light transmissive member 403 and a housing 404.
The light transmissive member 403 covers the luminous flux emitting surface of the reflector 402. The housing 404 houses the light source 401, reflector 402 and light transmissive member 403. The reflector 402 is provided with an aperture part 402A, while the housing 404 is provided with an aperture part 404A.
The aperture part 404A in the housing 404 is provided at a position opposed to the aperture part 402A in the reflector 402. The aperture part 404A is coupled to a duct 405 with an opening on the luminous flux emitting surface side.
When the light source device 400 is attached to an optical apparatus, the duct 405 juts from the luminous flux emitting surface so as to couple to a fan 410. With this action, the aperture part 404A is opened and air from the fan 410 is drawn into the reflector 402 as shown by arrow A. The air drawn into the reflector 402 then passes through the reflector 402 and is released from an aperture part 402B of the reflector 402 as shown by arrow B, thereby cooling the light source 401.
However, the conventional light source device as disclosed in JP No. 2004-258211 has a problem of low cooling efficiency since the air drawn into the reflector passes near the luminous flux emitting surface that is away from the light emitting point.
The conventional light source device also has a problem that the reflector if made of glass, may sustain damage by the possible explosion of the lamp.